Light emitting diodes with enhanced thermal sinking and associated methods of operation

ABSTRACT

Solid state lighting devices and associated methods of thermal sinking are described below. In one embodiment, a light emitting diode (LED) device includes a heat sink, an LED die thermally coupled to the heat sink, and a phosphor spaced apart from the LED die. The LED device also includes a heat conduction path in direct contact with both the phosphor and the heat sink. The heat conduction path is configured to conduct heat from the phosphor to the heat sink.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/516,214, filed Jul. 18, 2019, now U.S. Pat. No. 11,239,403; which isa divisional of U.S. application Ser. No. 15/652,632, filed Jul. 18,2017, now U.S. Pat. No. 10,403,805; which is a divisional of U.S.application Ser. No. 14/992,787, filed Jan. 11, 2016, now U.S. Pat. No.9,748,461; which is a divisional of U.S. application Ser. No.13/774,502, filed Feb. 22, 2013, now U.S. Pat. No. 9,236,550; which is adivisional of U.S. application Ser. No. 12/727,943, filed Mar. 19, 2010,now U.S. Pat. No. 8,384,105; each of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure is related to solid state lighting (SSL) devicesand associated methods of operation. In particular, the presentdisclosure is related to light emitting diodes (LEDs) and associatedmethods of heat sinking.

BACKGROUND

Mobile phones, personal digital assistants (PDAs), digital cameras, MP3players, and other portable electronic devices utilize SSL devices(e.g., white light LEDs) for background illumination. SSL devices arealso used for signage and general illumination. However, true whitelight LEDs are not available because LEDs typically only emit at oneparticular wavelength. For human eyes to perceive the color white, amixture of wavelengths is needed.

One conventional technique for emulating white light with LEDs includesdepositing a converter material (e.g., a phosphor) on a light emittingmaterial. For example, as shown in FIG. 1A, a conventional LED device 10includes a support 2 carrying an LED die 4 and a converter material 6deposited on the LED die 4. The LED die 4 can include one or more lightemitting components. For example, as shown in FIG. 1B, the LED die 4 caninclude a silicon substrate 12, N-type gallium nitride (GaN) material14, an indium gallium nitride (InGaN) material 16 (and/or GaN multiplequantum wells), and a P-type GaN material 18 on one another in series.The LED die 4 can also include a first contact 20 on the P-type GaNmaterial 18 and a second contact 22 on the N-type GaN material 14.Referring to both FIGS. 1A and 1B, in operation, the InGaN material 16of the LED die 4 emits a blue light that stimulates the convertermaterial 6 to emit a light (e.g., a yellow light) at a desiredfrequency. The combination of the blue and yellow emissions appearswhite to human eyes if matched appropriately.

One operational difficulty of the LED device 10 is that the LED die 4produces a significant amount of heat during operation. The generatedheat raises the temperature of the converter material 6, and thusreduces the efficiency of the converter material 6 to convert theemitted light from the LED die 4 (a phenomenon commonly referred to as“thermal quenching”). As a result, the combined emissions would appearoff-white and may reduce the color fidelity of electronic devices.Accordingly, several improvements in thermal sinking structures for LEDdevices may be desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross-sectional diagram of an LED device inaccordance with the prior art.

FIG. 1B is a schematic cross-sectional diagram of an LED die inaccordance with the prior art.

FIGS. 2A-2D are schematic cross-sectional diagrams of an LED device witha single layer of conduction material in accordance with embodiments ofthe technology.

FIGS. 3A and 3B are schematic cross-sectional diagrams of an LED devicewith a plurality of layers of conduction material in accordance withembodiments of the technology.

FIGS. 4A-4C are schematic cross-sectional diagrams of an LED device witha plurality of LED dies in accordance with embodiments of thetechnology.

DETAILED DESCRIPTION

Various embodiments of SSL devices and associated methods of thermalsinking are described below. The term “LED” generally refers to asemiconductor diode that converts electrical energy into electromagneticradiation, for example, in visible, ultraviolet, and/or infraredspectra. The term “phosphor” generally refers to a material that cancontinue emitting light after exposure to energized particles (e.g.,electrons and/or photons). A person skilled in the relevant art willalso understand that the technology may have additional embodiments andthat the technology may be practiced without several of the details ofthe embodiments described below with reference to FIGS. 2A-4C.

FIG. 2A is a schematic cross-sectional diagram of an LED device 100 inaccordance with embodiments of the technology. As shown in FIG. 2A, theLED device 100 includes a substrate 102, an LED die 104, an insulatingmaterial 106, a conduction material 108, and a converter material 110adjacent to one another in series. Even though only the foregoingcomponents of the LED device 100 are shown in FIG. 2A, in otherembodiments, the LED device 100 can also include an encapsulant, a lens,color filters, and/or other suitable peripheral components.

The substrate 102 can include a heat sink with a thermal conductivitygreater than about 1.0 W/(m·K) to transfer heat from the LED die 104and/or the converter material 110. For example, in certain embodiments,the substrate 102 can include silicon (Si), gallium nitride (GaN),aluminum nitride (AlN), and/or other suitable semiconductor materials.In other embodiments, the substrate 102 can include copper (Cu),aluminum (Al), tungsten (W), stainless steel, and/or other suitablemetal and/or metal alloys. In further embodiments, the substrate 102 caninclude diamond, glass, quartz, silicon carbide (SiC), aluminum oxide(Al₂O₃), and/or other suitable crystalline or ceramic materials.

The LED die 104 can include a single LED or a plurality of LEDs arrangedin an array. The LED die 104 can be configured to emit in the visiblespectrum (e.g., from about 565 nm to about 660 nm), in the infraredspectrum (e.g., from about 680 nm to about 970 nm), in the near infraredspectrum (e.g., from about 1050 nm to about 1550 nm), and/or in othersuitable spectra via an emission area 105. In one embodiment, the LEDdie 104 can have structures and functions generally similar to those ofthe LED die 4 shown in FIG. 1B. In other embodiments, the LED die 104can have other suitable structures and/or functions.

The insulating material 106 can at least partially encapsulate the LEDdie 104 to thermally insulate the converter material 110 from the LEDdie 104. Thus, the insulating material 106 can be generally transparentand having a low thermal conductivity. For example, in certainembodiments, the insulating material 106 can have a thermal conductivityless than about 0.5 W/(m·K). In other embodiments, the insulatingmaterial 106 can have a thermal conductivity less than about 0.15W/(m·K). In further embodiments, the insulating material 106 can haveother suitable thermal conductivities. The insulating material 106 caninclude a polyimide, a solvent-soluble thermoplastic polyimide, otherpolymers, ceramics, glasses, and/or other suitable thermally insulativematerials.

As shown in FIG. 2A, the conduction material 108 includes a lateralportion 1081 and two vertical portions 108 v extending from the lateralportion 1081 toward and in direct contact with the substrate 102. Theconduction material 108 can be generally transparent at least in theemission spectra of the LED die 104. The conduction material 108 canalso be thermally conductive. For example, the conduction material 108can have a thermal conductivity of greater than about 1.0 W/(m·K), about10.0 W/(m·K), about 100.0 W/(m·K), or other suitable conductivityvalues.

In one embodiment, the conduction material 108 can include a layer ofindium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide(ZnO), and/or other suitable inorganic transparent conducting oxides(TCOs). In other embodiments, the conduction material 108 can alsoinclude organic films of transparent conductive polymers. Examples ofsuch transparent conductive polymers includepoly(3,4-ethylenedioxythiophene),poly(4,4-dioctylcyclopentadithiophene), and/or other doped or undopedderivatives thereof. In further embodiments, the conduction material 108can also include other suitable transparent and thermally conductivematerials.

The converter material 110 can have a composition that emits at adesired wavelength under stimulation such that a combination of theemission from the LED die 104 and the converter material 110 can emulatea white light. For example, in one embodiment, the converter material110 can include a phosphor containing cerium(III)-doped yttrium aluminumgarnet (YAG) at a particular concentration for emitting a range ofcolors from green to yellow and to red under photoluminescence. In otherembodiments, the converter material 110 can include neodymium-doped YAG,neodymium-chromium double-doped YAG, erbium-doped YAG, ytterbium-dopedYAG, neodymium-cerium double-doped YAG, holmium-chromium-thuliumtriple-doped YAG, thulium-doped YAG, chromium(IV)-doped YAG,dysprosium-doped YAG, samarium-doped YAG, terbium-doped YAG, and/orother suitable phosphor compositions. In yet other embodiments, theconverter material 110 can include europium phosphors (e.g., CaS:Eu,CaAlSiN₃:Eu, Sr₂Si₅N₈:Eu, SrS:Eu, Ba₂Si₅N₈:Eu, Sr₂SiO₄:Eu, SrSi₂N₂O₂:Eu,SrGa₂S₄:Eu, SrAl₂O₄:Eu, Ba₂SiO₄:Eu, Sr₄Al₄O₂₅:Eu, SrSiAl₂O₃N:Eu,BaMgAl₁₀O₁₇:Eu, Sr₂P₂O₇:Eu, BaSO₄:Eu, and/or SrB₄O₇:Eu).

During an initial stage of an assembly process, the LED die 104 can bephysically and thermally coupled to the substrate 102 with a conductiveepoxy adhesive (e.g., model No. TC-2707 provided by 3M of St. Paul,Minn.), a metallic solder material (e.g., a gold/tin solder), and/orother suitable adhesive materials (not shown). The insulating material106 can then be formed on the LED die 104 and the substrate 102 via spincoating, chemical vapor deposition (CVD), and/or other suitabletechniques. The conduction material 108 can then be formed on theinsulating material 106 via physical vapor deposition (PVD, e.g.,sputtering), pulsed laser deposition (PLD), and/or other suitabletechniques. Subsequently, the converter material 110 may be formed onthe conduction material 108 via spin coating, screen printing, and/orother suitable techniques.

In operation, electrical power is provided to the LED die 104 from anexternal source (not shown). The LED die 104 produces a first emissionat a first wavelength from the emission area 105. The first emissionfrom the LED die 104 passes through the transparent insulating material106 and the conduction material 108 to reach the converter material 110.The converter material 110 then produces a second emission at a secondwavelength under the stimulation of the first emission. The secondemission then combines with the first emission to produce a light atleast approximating a white light.

The LED die 104 also generates heat while producing the first emission.The generated heat from the LED die 104 is at least partially conductedaway via the substrate 102 while the insulating material 106 at leastreduces a heat flux flowing from the LED die 104 to the convertermaterial 110. Even though the combination of the substrate 102 and theinsulating material 106 may partially shield the converter material 110from the heat produced by the LED die 104, the inventors have recognizedthat the converter material 110 itself also generates heat whileproducing the second emission. For example, the converter material 110(e.g., cerium(III)-doped YAG) typically has a conversion rate (i.e., apercentage of produced emission per unit input) of about 75% to about80% with the remaining input energy converted to heat. If the generatedheat from the converter material 110 is not adequately dissipated,thermal quenching may still occur.

The inventors also recognized that the converter material 110 typicallyhas low thermal conductivities. As a result, it is believed that theconverter material 110 itself cannot conduct a sufficient amount of heataway to the substrate 102 even though the converter material 110 is indirect contact with the substrate 102. Thus, by interposing theconduction material 108 between the insulating material 106 and theconverter material 110, the conduction material 108 may efficientlyconduct at least (1) a portion of the heat generated by the LED die 104and (2) the heat generated by the converter material 110 to thesubstrate 102. Accordingly, the risk of thermal quenching in theconverter material 110 may be reduced or even eliminated.

Even though the LED device 100 shown in FIG. 2A has the conductionmaterial 108 interposed between the insulating material 106 and theconverter material 110, in certain embodiments, as shown in FIG. 2B, theconduction material 108 can be spaced apart from the insulating material106. As a result, the converter material 110 is interposed between theconduction material 108 and the insulating material 106.

In other embodiments, as shown in FIG. 2C, the insulating material 106may be eliminated. As a result, the conduction material 108 isinterposed directly between the converter material 110 and the LED die104. In these embodiments, the LED die 104 may optionally include anelectrical insulator 107 in direct contact with the conduction material108. The electrical insulator 107 can include silicon dioxide (SiO₂),silicon nitride (SiN), and/or other suitable electrically insulatingmaterials. In operation, the conduction material 108 conducts both (1) aportion of the heat generated by the LED die 104 and (2) the heatgenerated by the converter material 110 to the substrate 102.

The converter material 110 in FIGS. 2A-2C is shown to generallyencapsulate an underlying material (e.g., the conduction material 108 inFIG. 2A). However, in other embodiments, as shown in FIG. 2D, theconverter material 110 may be formed only on a surface 109 of theconduction material 108. The surface 109 of the conduction material 108faces away from the LED die 104. The converter material 110 may have awidth W generally corresponding to the emission area 105 of the LED die104 and/or other suitable widths. In further embodiments, the convertermaterial 110 may have other configurations, as described in more detailbelow with reference to FIGS. 3A-4C.

FIGS. 3A and 3B are schematic cross-sectional diagrams of an LED device200 with a plurality of layers of conduction material in accordance withembodiments of the technology. The LED device 200, and other LED devicesdescribed herein, can include structures with functions generallysimilar to those described above with reference to FIGS. 2A-2D. As such,common acts and structures are identified by the same reference numbers.Only significant differences in operation and structure are describedbelow.

As shown in FIG. 3A, the LED device 200 can include components generallysimilar to the LED device 100 of FIG. 2A except that the LED device 200includes a first conduction material 108 a and a second conductionmaterial 108 b separated from each other by the converter material 110.As a result, the first conduction material 108 a is in direct contactwith a first surface 110 a of the converter material 110. The secondconduction material 108 b is in direct contact with a second surface 110b of the converter material 110.

In certain embodiments, the first and second conduction materials 108 aand 108 b can include generally the same material (e.g., ITO) with agenerally similar thickness. In other embodiments, the first and secondconduction materials 108 a and 108 b can include different materials.For example, the first conduction material 108 a includes ITO, and thesecond conduction material 108 b includes FTO. In further embodiments,the first and second conduction materials 108 a and 108 b can includethe same material with different thicknesses and/or other physicalcharacteristics.

It is believed that the first and second conduction materials 108 a and108 b can improve the temperature homogeneity in the converter material110 in a direction (as represented by the Y-axis) generallyperpendicular to the first and second surfaces 110 a and 110 b of theconverter material 110. It is believed that the converter material 110may have internal temperature gradients along the Y-axis duringoperation due to low thermal conductivities. For example, if thegenerated heat is conducted away from only one surface (e.g., the firstsurface 110 a) of the converter material 110, the opposing surface(e.g., the second surface 110 b) of the converter material 110 may be ata higher temperature than the heat-conducting surface. As a result, theportion of the converter material 110 proximate to the second surface110 b may still suffer from thermal quenching. Accordingly, byconducting heat away from both the first and second surfaces 110 a and110 b along two heat conduction paths formed by the first and secondconduction materials 108 a and 108 b, the temperature profile of theconverter material 110 along the Y-axis may be more homogeneous thanconducting heat from only one surface of the converter material 110.

FIG. 3B is a schematic cross-sectional diagram of the LED device 200with further improved temperature homogeneity in the converter material110. As shown in FIG. 3B, the LED device 200 includes a plurality ofvias 112 in the converter material 110 and individually holding a thirdconduction material 108 c. In the illustrated embodiment, the vias 112individually include a generally linear passage extending directlybetween the first and second conduction materials 108 a and 108 b. Inother embodiments, the vias 112 can also include a serpentine passage, astepped passage, and/or other suitable configurations. The first,second, and third conduction materials 108 a, 108 b, and 108 c mayinclude the same material (e.g., ITO) or may include different materialsand/or physical characteristics.

It is believed that the third conduction material 100 c can furtherimprove the temperature homogeneity in the converter material 110 byequalizing temperature gradients in another direction (as represented bythe X-axis) generally parallel to the first and second surfaces 110 aand 110 b. It is believed that the converter material 110 may haveinternal temperature gradients not only along the Y-axis, as discussedabove, but also along the X-axis during operation due to its low thermalconductivities. As a result, one portion of the converter material 110may still experience thermal quenching when another portion laterallyspaced apart is operating normally. Accordingly, by having a pluralityof vias 112 along the X-axis, the third conduction material 108 c mayform another heat conduction path generally perpendicular to thoseformed by the first and second conduction materials 108 a and 108 b.Thus, the temperature profile of the converter material 110 along theX-axis may be more homogeneous than without such conduction paths.

Even though only one converter material 110 is shown in FIGS. 3A and 3B,in certain embodiments, the LED device 200 can also include a pluralityof repeating patterns of the first conduction material 108 a, theconverter material 110, and the second conduction material 108 b formedon one another in series. In other embodiments, the repeating patternsmay also include the third conduction material 108 c (as shown in FIG.3B). In further embodiments, the LED device 200 may include more thanone LED die 104, as described in more detail below with reference toFIGS. 4A-4C.

FIGS. 4A-4C are schematic cross-sectional diagrams of an LED device 300with a plurality of LED dies in accordance with embodiments of thetechnology. Two LED dies are shown in FIGS. 4A-4C for illustrationpurposes even though the LED device 300 may include three, four, or anyother desired number of LED dies for certain applications.

As shown in FIG. 4A, the LED device 300 includes a first LED die 104 aand a second LED die 104 b carried by the substrate 102 in aside-by-side arrangement. A first insulating material 106 a and a firstconduction material 108 a are formed on the first LED die 104 a. Asecond insulating material 106 b and a second conduction material 108 bare formed on the second LED die 104 b. In the illustrated embodiment,the first and second LED dies 104 a and 104 b may be generally similarin structure and function. In other embodiments, the first and secondLED dies 104 a and 104 b may have different structures and/or functions.

The LED device 300 can also include a converter material 110encapsulating the first and second conduction materials 108 a and 108 b.Thus, the converter material 110 can include a first portion 110 agenerally corresponding to the first LED die 104 a, a second portion 110b generally corresponding to the second LED die 104 b, and a thirdportion 110 c between the first and second LED dies 104 a and 104 b.During assembly, dams 114 (shown in phantom lines for clarity) may beplaced against the substrate 102, and the converter material 110 may bespin coated, injected, and/or otherwise applied to fill the spacebetween the dams 114 and the substrate 102. In other embodiments, theconverter material 110 may be formed via other suitable techniques withor without the dams 114.

Optionally, the LED device 300 may also include an aperture 115 in thethird portion 110 c of the converter material 110. The aperture 115 mayhold a conduction material 117 that is in direct contact with thesubstrate 102. During assembly, the optional aperture 115 may be formedvia patterning the converter material 110 via photolithography, andremoving a portion of the converter material 110 from the third portion110 c via dry etching, wet etching, and/or other suitable materialremoval techniques. In further embodiments, the aperture 115 may beomitted.

FIG. 4B illustrates another embodiment of the LED device 300 in whichthe conduction material 108 encapsulates both the first and secondinsulating materials 106 a and 106 b. As a result, the conductionmaterial 108 includes a first portion 108 a generally corresponding tothe first LED die 104 a, a second portion 108 b generally correspondingto the second LED die 104 b, and a third portion 108 c between the firstand second LED dies 104 a and 104 b.

FIG. 4C illustrates an additional embodiment of the LED device 300 inwhich the insulating material 106 encapsulates the first and second LEDdies 104 a and 104 b. As a result, the insulating material 106 includesa first portion 106 a generally corresponding to the first LED die 104a, a second portion 106 b generally corresponding to the second LED die104 b, and a third portion 106 c between the first and second LED dies104 a and 104 b.

From the foregoing, it will be appreciated that specific embodiments ofthe technology have been described herein for purposes of illustration,but that various modifications may be made without deviating from thedisclosure. For example, even though the LED device 300 is shown inFIGS. 4A-4C as having one conduction material 108, in certainembodiments, the LED device 300 may also include two or more conductionmaterials, for example, as described above with reference to FIGS. 3Aand 3B. In addition, many of the elements of one embodiment may becombined with other embodiments in addition to or in lieu of theelements of the other embodiments. Accordingly, the disclosure is notlimited except as by the appended claims.

We claim:
 1. A solid state lighting (SSL) device, comprising: asubstrate; a plurality of SSL dies carried by the substrate, whereineach of the plurality of SSL dies includes an emissions area and isencapsulated by and in direct contact with a discrete layer ofinsulating material, the layer of insulating material being at leastpartially transparent; a monolithic layer of conduction materialencapsulating each of the plurality of SSL dies and completely filling aspace laterally separating adjacent ones of the plurality of SSL dies,the conduction material in direct contact with the substrate under thespace; a converter material disposed over the monolithic layer ofconduction material and positioned in line with the emissions area ofeach of the plurality of SSL dies such that emissions from the pluralityof SSL dies pass through the converter material.
 2. The SSL device ofclaim 1 wherein the substrate has a thermal conductivity greater thanabout 1.0 W/(m·K).
 3. The SSL device of claim 1 wherein the conductionmaterial has a thermal conductivity greater than about 1.0 W/(m·K). 4.The SSL device of claim 1 wherein the conduction material is at leastpartially transparent.
 5. The SSL device of claim 1 wherein themonolithic layer of conduction material includes a first portiongenerally corresponding to a first SSL of the plurality, a secondportion generally corresponding to a second SSL of the plurality, and athird portion corresponding to the space.
 6. The SSL device of claim 1wherein the substrate includes at least one of silicon (Si), galliumnitride (GaN), aluminum nitride (AlN), copper (Cu), aluminum (Al),tungsten (W), stainless steel (Fe), diamond (C), glass (SiO₂), siliconcarbide (SiC), and aluminum oxide (Al₂O₃).
 7. The SSL device of claim 1wherein the converter material includes a plurality of conductivematerials positioned therein.
 8. The SSL device of claim 1 wherein eachof the plurality of SSL dies includes an N-type gallium nitride (GaN)material, an indium gallium nitride (InGaN) material, and a P-type GaNmaterial on one another in series.
 9. The SSL device of claim 1 whereinthe converter material includes a phosphor.
 10. The SSL device of claim9 wherein the phosphor includes at least one of cerium(III)-dopedyttrium aluminum garnet (“YAG”), neodymium-doped YAG, neodymium-chromiumdouble-doped YAG, erbium-doped YAG, ytterbium-doped YAG,neodymium-cerium double-doped YAG, holmium-chromium-thulium triple-dopedYAG, thulium-doped YAG, chromium(IV)-doped YAG, dysprosium-doped YAG,samarium-doped YAG, and terbium-doped YAG, CaS:Eu, CaAlSiN₃:Eu,Sr₂Si₅N₈:Eu, SrS:Eu, Ba₂Si₅N₈:Eu, Sr₂SiO₄:Eu, SrSi₂N₂O₂:Eu, SrGa₂S₄:Eu,SrAl₂O₄:Eu, Ba₂SiO₄:Eu, Sr₄Al₁₄O₂₅:Eu, SrSiAl₂O₃N:Eu, BaMgAl₁₀O₁₇:Eu,Sr₂P₂O₇:Eu, BaSO₄:Eu, and SrB₄O₇:Eu.
 11. The SSL device of claim 1wherein the conductive material includes at least one of indium tinoxide (ITO), fluorine-doped tin oxide (FTO), and zinc oxide (ZnO).
 12. Asolid state lighting (SSL) device, comprising: a substrate; a pluralityof SSL dies carried by the substrate, wherein each of the plurality ofSSL dies includes an emissions area and is encapsulated by and in directcontact with a discrete layer of insulating material, the layer ofinsulating material being at least partially transparent; a conductionmaterial encapsulating each of the plurality of SSL dies and disposed ina space laterally separating adjacent ones of the plurality of SSL dies,the conduction material in direct contact with the substrate under thespace; a converter material disposed over each of the plurality of SSLdies and in direct contact with the conduction material, the convertermaterial positioned in line with the emissions area of each of theplurality of SSL dies such that emissions from the plurality of SSL diespass through the converter material.
 13. The SSL device of claim 12wherein the substrate has a thermal conductivity greater than about 1.0W/(m·K).
 14. The SSL device of claim 12 wherein the conduction materialhas a thermal conductivity greater than about 1.0 W/(m·K).
 15. The SSLdevice of claim 12 wherein the conduction material is at least partiallytransparent.
 16. The SSL device of claim 12 wherein the conductionmaterial includes a first portion generally corresponding to a first SSLof the plurality, a second portion generally corresponding to a secondSSL of the plurality, and a third portion disposed in an aperturelocated in the space.
 17. The SSL device of claim 12 wherein thesubstrate includes at least one of silicon (Si), gallium nitride (GaN),aluminum nitride (AlN), copper (Cu), aluminum (Al), tungsten (W),stainless steel (Fe), diamond (C), glass (SiO₂), silicon carbide (SiC),and aluminum oxide (Al₂O₃).
 18. The SSL device of claim 12 wherein theconverter material includes a plurality of conductive materialspositioned therein.
 19. The SSL device of claim 12 wherein each of theplurality of SSL dies includes an N-type gallium nitride (GaN) material,an indium gallium nitride (InGaN) material, and a P-type GaN material onone another in series.
 20. The SSL device of claim 12 wherein theconverter material includes a phosphor.